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Prevent use-after-free of TransactionPlugin #6937

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Merged
sudheerv merged 1 commit into from
Jun 24, 2020
Merged

Prevent use-after-free of TransactionPlugin #6937

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2 changes: 2 additions & 0 deletions include/tscpp/api/TransactionPlugin.h
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Original file line number Diff line number Diff line change
Expand Up @@ -118,6 +118,8 @@ class TransactionPlugin : public Plugin
*/
std::shared_ptr<Mutex> getMutex();

std::shared_ptr<Mutex> getMutex(TSHttpTxn);

private:
TransactionPluginState *state_; /**< The internal state for a TransactionPlugin */
friend class utils::internal;
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6 changes: 6 additions & 0 deletions src/tscpp/api/TransactionPlugin.cc
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Expand Up @@ -71,6 +71,12 @@ TransactionPlugin::getMutex()
return state_->mutex_;
}

std::shared_ptr<Mutex>
TransactionPlugin::getMutex(TSHttpTxn txnp)
{
return state_->ats_txn_handle_ == txnp ? state_->mutex_ : nullptr;
}

bool
TransactionPlugin::isWebsocket() const
{
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16 changes: 10 additions & 6 deletions src/tscpp/api/utils_internal.cc
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Expand Up @@ -58,10 +58,14 @@ cleanupTransaction(Transaction &transaction, TSHttpTxn ats_txn_handle)
}

void
cleanupTransactionPlugin(Plugin *plugin)
cleanupTransactionPlugin(Plugin *plugin, TSHttpTxn ats_txn_handle)
{
TransactionPlugin *transaction_plugin = static_cast<TransactionPlugin *>(plugin);
std::shared_ptr<Mutex> trans_mutex = utils::internal::getTransactionPluginMutex(*transaction_plugin);
std::shared_ptr<Mutex> trans_mutex = utils::internal::getTransactionPluginMutex(*transaction_plugin, ats_txn_handle);
if (trans_mutex == nullptr) {
LOG_ERROR("TransactionPlugin use-after-free! plugin %p, txn %p", plugin, ats_txn_handle);
return;
}
LOG_DEBUG("Locking TransactionPlugin mutex to delete transaction plugin at %p", transaction_plugin);
trans_mutex->lock();
delete transaction_plugin;
Expand Down Expand Up @@ -96,7 +100,7 @@ handleTransactionEvents(TSCont cont, TSEvent event, void *edata)
resetTransactionHandles(transaction, event);
const std::list<TransactionPlugin *> &plugins = utils::internal::getTransactionPlugins(transaction);
for (auto plugin : plugins) {
cleanupTransactionPlugin(plugin);
cleanupTransactionPlugin(plugin, ats_txn_handle);
}
cleanupTransaction(transaction, ats_txn_handle);
} break;
Expand Down Expand Up @@ -158,7 +162,7 @@ void inline invokePluginForEvent(Plugin *plugin, TSHttpTxn ats_txn_handle, TSEve
case TS_EVENT_HTTP_TXN_CLOSE:
if (plugin) {
plugin->handleTxnClose(transaction);
cleanupTransactionPlugin(plugin);
cleanupTransactionPlugin(plugin, ats_txn_handle);
} else {
LOG_ERROR("stray event TS_EVENT_HTTP_TXN_CLOSE, no transaction plugin to handle it!");
}
Expand All @@ -185,9 +189,9 @@ utils::internal::getTransaction(TSHttpTxn ats_txn_handle)
}

std::shared_ptr<Mutex>
utils::internal::getTransactionPluginMutex(TransactionPlugin &transaction_plugin)
utils::internal::getTransactionPluginMutex(TransactionPlugin &transaction_plugin, TSHttpTxn txnp)
{
return transaction_plugin.getMutex();
return transaction_plugin.getMutex(txnp);
}

TSHttpHookID
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2 changes: 1 addition & 1 deletion src/tscpp/api/utils_internal.h
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Expand Up @@ -55,7 +55,7 @@ namespace utils
static HttpVersion getHttpVersion(TSMBuffer hdr_buf, TSMLoc hdr_loc);
static void initTransactionManagement();
static std::string consumeFromTSIOBufferReader(TSIOBufferReader);
static std::shared_ptr<Mutex> getTransactionPluginMutex(TransactionPlugin &);
static std::shared_ptr<Mutex> getTransactionPluginMutex(TransactionPlugin &, TSHttpTxn);
static Transaction &getTransaction(TSHttpTxn);

static AsyncHttpFetchState *
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